Effects of chronic exposure to cadmium on prostate lipids and morphology

Abstract

Cadmium is an environmental toxic metal implicated in human prostate carcinogenesis. The mechanism of its toxicity is not fully understood. Previously, we showed that cadmium exposure induces oxidative stress, especially lipid peroxidation. This study evaluates the effect of chronic exposure to 0.886 mM of cadmium (Cd) per liter in the drinking water on prostate lipid content and metabolism in Wistar rats. We determined the lipid profile and measured the expression of lipogenic enzymes: FAS, GPAT, LPL, DGAT-1, DGAT-2, ACO, CPT-1 and CT, and of certain factors involved in lipid regulation and fatty acid transporters: FAT/CD36, E-FABP, SREBP-2, PPAR-γ and PPAR-α by RT-PCR. Ultrastructure was analyzed by electron microscopy and, as prostate is an androgen controlled gland, AR expression was measured by RT-PCR and Western blot. Cd altered the prostatic lipid profile. Triglycerides (TG) and esterified cholesterol (EC) decreased, free cholesterol (FC) and phospholipids (PL) increased and total cholesterol (TC) did not change. FAS, MDH and IDH activities did not vary but G6PDH decreased significantly in Cd group. Regarding TG synthesis, DGAT-1 decreased while GPAT increased and FAS, LPL and DGAT-2 remained unchanged. Regarding beta oxidation, CPT-1 increased while ACO expression decreased in Cd group. In the PL pathway, CT expression was increased. All these results would justify the decrease of TG in Cd group when compared to control. In the cholesterol metabolic pathway, HMGCoAR and SREBP-2 increased. PPAR-α increased but PPAR-γ did not change. Regarding fatty acid transporters, FAT/CD36 decreased, while E-FABP increased. AR mRNA and protein expression decreased. Ultrastructural analysis showed a decrease in lipid droplets and signs of cellular damage in the Cd group.

Cadmium exposure induces important changes in prostatic lipid profile and metabolism, confirmed by the morphology analyses, which also showed signs of cellular damage. These results could be important to further understanding the complex mechanism of cadmium toxicity in prostate and in the development of better treatments for people and animals exposed to the heavy metal.

Keywords

androgens cadmium lipids oxidative stress rat prostate

Abbreviations

LD50

medial lethal doses

FAS

fatty acid synthetase

HMGCoAR

hydroxymethylglutaryl coenzyme A reductase

GPAT

glycerol-3-phosphate acyltransferase

DGAT

diacyl glycerol acyl transferase

LPL

lipoprotein lipase

FC

free cholesterol

EC

esterified cholesterol

TG

triglycerides

AR

androgen receptor

CT

CTP-phosphocholine cytidylyltransferase

DAG

diacyl glycerol

ACO

acyl CoA oxidase

CPT-1

carnitin palmitoil transferase

PC

phosphatidilcholine

FA

fatty acids

TBARS

thiobarbituric acid – reactive susbtances

Fellowship from the National Council of Scientific and Technical Investigations (CONICET) – Argentina.

Career Scientific Investigator. National Council of Scientific and Technical Investigations (CONICET) – Argentina.

Notes

Acknowledgments

This work has been supported by grant, PIP 4931 from CONICET (National Investigation Council of Science and Technology, Argentina), and Project 8104 from San Luis University, Argentina. MSG, MWF are Career Scientists from CONICET, and SMA has fellowship from CONICET. Authors would like to thank Miss Isabel Sosa, Mr. R. Dominguez for their technical assistance, Dr. Luis D. Martinez for the analysis of cadmium content by ICP-AES in water and prostate samples and Dr. Graciela Jahn and Dr. Silvia Varas for critical reading of the manuscript.

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